This invention relates to height or displacement adjustment mechanisms for chairs and similar fixtures, and more particularly relates to mechanisms for adjusting the height of chairs which are designed to swivel without altering the previously adjusted height of the chair seat.
In order to selectively adjust the height of a chair seat, tabletop or similar fixture, relative to the base of the fixture, numerous height adjustment mechanisms have been developed as described, for example, in U.S. Pat. Nos. 3,161,396; 3,711,054; 3,741,514 and 3,778,014. Since modern office chairs are designed to allow swiveling of the seat without modifying the height of the seat which the user wishes to maintain, the arrangement of the height adjustment mechanism must also enable such swiveling. Further height adjustment mechanisms incorporating a threaded screw and nut arrangement for swiveling chairs are described for example in U.S. Pat. Nos. 3,386,697; 3,799,485; 4,113,220; 4,261,540; and 4,493,469.